Investigation of Thermal Inertia and Surface Properties for Near-Earth Asteroid (162173) 1999 JU3

TL;DR

This study uses thermal modeling to estimate the surface properties and thermal inertia of asteroid 1999 JU3, providing insights into its surface composition and confirming the feasibility of Hayabusa 2's sample return mission.

Contribution

It presents a detailed thermal inertia distribution and surface composition inference for asteroid 1999 JU3 using the ATPM, aiding mission planning and scientific understanding.

Findings

Effective diameter: 1.13 km

Average thermal inertia: 300 J·m⁻²·s⁻⁰·⁵·K⁻¹

Surface likely covered by loose materials

Abstract

In order to obtain the substantial information about the surface physics and thermal property of the target asteroid (162173) 1999 JU3, which will be visited by Hayabusa 2 in a sample return mission, with the Advanced Thermal Physical Model (ATPM) we estimate the possible thermal inertia distribution over its surface, and infer the major material composition of its surface materials. In addition, the effective diameter and geometric albedo are derived to be $D_{\rm eff}=1.13\pm0.03\rm~km$, $p_{\rm v}=0.042\pm0.003$, respectively, and the average thermal inertia is estimated to be about $(300\pm50)\rm~J\cdot m^{-2}\cdot s^{-0.5}\cdot K^{-1}$. According to the derived thermal inertia distribution, we infer that the major area on the surface of the target asteroid may be covered by loose materials, such as rock debris, sands, and so on, but few bare rocks may exist in a very small region. In this sense, the sample return mission of Hayabusa 2 is feasible, when it is performed successfully, it will certainly bring significant scientific information to the research of asteroids.